Muscle-strengthening exercise and positive mental health in children and adolescents: An urban survey study.

Background: Much evidence has indicated that physical activity is associated with mental health benefits, such as fewer depression symptoms. Psychological resilience captures a broader mental health phenomenon that may be influenced by other factors as well. Yet, there are few studies examining the association between muscle-strengthening exercises (MSEs) with mental health outcomes, especially positive outcomes (e.g., subjective wellbeing). The study aimed to test the association between MSE with subjective wellbeing and resilience among a large sample of Chinese adolescents. Materials and methods: A cross-sectional study was conducted among primary and middle school students in Shenzhen, China. MSE frequency, subjective wellbeing, and resilience were measured. Data from a total of 67,281 children and adolescents aged 10-17 years (51.9% men and 48.1% women) were included in the analysis. Mixed effect models were performed to assess how weekly MSE frequency (0-7 days) related to the levels of subjective wellbeing and resilience, adjusting for potential confounding variables (e.g., sex and grade). Sensitivity analyses were also conducted. Results: Compared to participants with no MSE, the levels of subjective wellbeing were higher in those with higher MSE frequencies [range of β: 0.29 (1 day per week) to 1.98 (7 days per week)]. The frequency of MSE was also positively correlated to better resilience [range of β: 0.50 (1 day per week) to 4.40 (7 days per week)]. All associations remained significant in sensitivity analyses. Conclusion: More frequent MSE was associated with superior subjective wellbeing and resilience of Chinese children and adolescents. Increasing MSE may be beneficial for promoting positive mental health outcomes among children and adolescents.